Xinjiang Institute of
Biology, Pedology and Desert Research
Desertification is one of the greatest environmental problems in the world today. The research on combating desertification is an important task for both the government and people. From the beginning of the establishment of the Xinjiang Institute of Biology, Pedology and Desert Research, all the research and practical work were focused on the development of techniques to combat desertification. The unceasing efforts of thirty years in combating desertification have made a lot of important achievement. It is hoped that the adapted technology and treatments can be used as the reference to those areas facing the similar problem in the affected regions.
With the total area of 337,600 square km, the Taklimakan Desert is the second largest sand desert in the world, and mobile dunes occupy 82.2% of its total area. Under the action of prevailing northwest and northeast winds, the desert constantly moves southward. In last two thousand years, the desert expanded southward nearly to a hundred kilometers, and the ancient Silk Road and historical towns were buried under shifting sands. Over a million people in seven counties and a city, living on the blown sand belt of approximate 1,000 sq. km at the southern margin of the desert, are seriously impacted by sand movement for a long time. Since this century, the desertification is further speeded up with the increase of irrational human activities. At the beginning of 1980’s, the sand movement in Cele County was the most serious among seven counties and city on the southern margin of the desert. Under the threats of sand transportation, Township of Cele County had been reconstructed for three times in the historical period. During last thirty years from the 1950’s to 1980’s, in the Cele Township located on the margin of the Cele Oasis, shifting dunes moved 5 km, the area of desertification-prone farmland was enlarged to 1,333 ha, occupying 25% of the total area of the cultivated land in the county and 60 households had to moved from their native town to a new location because of the dune movement and sand accumulation around their houses. Under the pressure of the desert and blown sand encroachment, the social economy and people’s living condition in Cele County were in backWardness and poverty. Desertification combating, sand dune stabilization and poverty alleviation were concerned as the major tasks of the local people of various ethnic nationalities and the agenda of with the local government.
To counter this serious situation, in October of 1982, the People’s Government of the Xinjiang Uygur Autonomous Region convened an on-the-spot meeting attended by the decision-makers, planners, coordinators and leaders of departments concerned of the Xinjiang People’s Government, the Xinjiang Branch of Chinese Academy of Sciences and the Hetian People’s Government, to discuss and review the local integrated development programme in the affected areas, for instance the stabilization of mobile dunes and blown sands in the Cele County. As a result of such consultation, Cele Sand-stabilization Research Station was established and jointly directed by the Hetian People’s Government and the Xinjiang Institute of Biology, Pedology and Desert Research, Chinese Academy of Sciences. An Experimental Study and Demonstration on Sand Stabilization in the Cele County was funded as a key project of Xinjiang. The Science and Technology Commission of Xinjiang, the Water Resources Department of Xinjiang, the Forestry Department of Xinjiang, and other departments provided financial supports respectively for carrying out research and practice on development of irrigation and dune stabilization and revegetation in the affected Cele County.
The project was implemented through contract system between local authorities and villagers. The time limit of the study stipulated by the contract was operated from 1983 to 1988, and the site was located at the margin of the Cele Oasis, its scale and aim were focused on the establishment of the demonstration for an area of 666.6 ha to rehabilitate the degraded 4,000 ha Of natural vegetation, and to increase the average vegetative coverage by 30-40%.
The project area is situated at the marginal area between the sand desert and oasis of the Cele County, Xinjiang. The annual mean precipitation is 35.1 mm, the annual mean evapotranspiration reaches 2,595.3 mm. With the total annual runoff of 585 million cubic metres, there are 9 seasonal rivers in the Cele County. However, the rainfall variation is different from season to season, of which 9.3% falls in the spring and 76.8% in the summer season. There is a great difference of rainfall between the rainy and dry seasons. The annual mean temperature is 11.9℃, the extremely maximum temperature is 41.9℃ and the extremely minimum temperature is 23.9℃ below zero. The main types of soil are aeolian soil, brown desert soil, and irrigation-warping soil. During the period of project implementation, the total area of degraded natural vegetation is 10,000 ha, have been rehabilitated, including 2,666 ha Of Populous Euphrates woodlands, 3,333 ha of Tamarix spp., 3,333 ha of Albania sparsifolia, and 666 ha of other herbs . An integrated protective demonstration with an area of 860.6 ha has been established, including 552.8 ha of sandbreak network, 71.1 ha of cash tree plantation, 200 ha of sand-fixing firewood plantation and 37.5 ha of crop farming land.
The project is mainly consisted of two parts, first one, the restoration and protection of 1,000 ha of natural vegetation. Before the operation of the project, the natural vegetation was severely damaged under the pressure of shortage of fuel energy resources, and vegetative coverage was reduced by 3-5%. After the implementation of the project, 50-60%; second one, an integrated protective system that consists of sandbreaks network, sand-fixing firewood plantation, cash tree plantation and crop farming land was established. Through the implementation of this project, desertification affected land has been transformed into cultivated land for corn, wheat and cotton harvests.
It is recorded that the Cele County Town（including the township of Yutian County）has been migrated three times from one location to another newly opened site during the historical period because of the encroachment of shifting dunes. From the 1950’s to the beginning of the 1980’s, sand dunes at the northwest fringe of the county was enlarged and encroached for 80-100 m every year. From 1957 to 1980, sand dunes near the Cele County Township have moved in an average annual rate of 5 kilometres. The gap between megadunes and township is only 1.5 km. The main cause of such sand transport and dune movement was the destruction of 2666.6 ha Populous euphratica woodlands and Tamarix spp. Communities under the pressure of blind reclaiming and excessive collection of fuelwood from the end of 1950’s to the early 1960’s. The fragile ecological environment has been seriously deteriorated by the acceleration of desertification. It was surveyed that before the operation of the project, the area of the desertified farmland accounted for 25% of total cultivated land of the county, and 60 households have been migrated from their native hometown to other places because of disasters of sand accumulation and vegetation destruction.
The following table shows the brief social and economic statistics of the Cele County. From the table, it can be evidently seen that the economy has been improved and the per capita income of villagers has been increased.
The vegetation change in the project area in the Cele County is as serious as other county, that is, the change is closely related to the development activities of human being, which weaken the functions of protection and restoration of vegetation. The vegetation changes were manifested in several stages. From 1949 to 1957, there were great amount of trees of diameters being tens cm to hundreds cm around villages and beside farmlands, and all corners were covered with green. Land was cultivated by private farmers for a long time, so the species, height and size of trees planted were different, and 80% of artificial plantation were made with private design and interests.
In early stages, fuelwood consumption was low, so the fuelwood source nearby settlements was enough for local cooking and heating. Furthermore, because of the limitation of traffic condition, fuelwood transport and marketing was not allowed, and lower price of the fuelwood limited long-distance transport of the fuelwood from the Gobi and deserts. The natural vegetation of Populus euphratica, Tamarix spp. etc, was basically in the state of natural maintenance. From 1958 to 1962, owing to destruction of vegetation caused by reclamation, the vegetation in desert was severely threatened. The artificial plantation inside oases was also blindly cut off. According to the statistic analysis, in this period of time, more than 700,000 high individual trees were cut off in the Cele County. In the stage from 1963 to 1967, artificial plantation was quickly re-launched, pioneer species were widely planted around the farmlands inside oasis, and artificial woodlands were replanted to some extent. However, during the period from 1968 to 1976, another wild cutting of plantation was re-occurred. After such disaster for green life, artificial plantation in oasis was completely destroyed, especially in the 1970’s, the damage of Populus euphratica woodlands in the desert was in serious stage. Because the wild cutting and deforestation inside the oasis, the consumption of timber and fuelwood were considerably increased with the quick enlargement of township and population growth. Since the beginning of the project execution, the natural vegetation was protected with rehabilitative approaches to control the above-mentioned wild cutting and deforestation. After longer period of times’ efforts, natural vegetation was quickly rehabilitated. At the same time, public awareness raising has been sponsored at local government level and the importance of vegetation protection was significantly recognized at grass-root level. After the formulation of state laws and regulations on nature preservation, forestry, environment and recourses management, some relative local regulations and rules have been developed, and special groups for taking care of forest protection, land preservation and environment protection have been organized at different levels and the effects for combating desertification and controlling land degradation were remarkable.
|
Year |
1973 |
1982 |
1988 |
|
Cultivated land area (104 ha) |
2.269 |
2.299 |
1.993 |
|
Cropping area (104 ha) |
1.696 |
1.698 |
1.33 |
|
Cereal yield (104 tons) |
2.3125 |
3.624 |
2.615 |
|
Cotton area (104 ha) |
0.106 |
0.139 |
0.244 |
|
Cotton yields (104 tons) |
0.02785 |
0.05 |
0.095 |
|
Oil crop area (104 ha) |
0.023 |
0.018 |
0.084 |
|
Oil crop yields (104 tons) |
0.0634 |
0.1393 |
0.065 |
|
Population (104 persons) |
8.7 |
9.9 |
11.21 |
|
Per capita (RMB Yuan) |
70 (in 1978) |
85 (in 1980) |
295 |
|
Total output of industry and agriculture (104 RMB Yuan) |
1,703.28 |
2,984 |
9,696 |
The pattern of land degradation in the project area is land desertification. The main cause of land desertification is the excessive economic activities of human being, caused by rapid population growth and low productivity level. Thus, in order to increase agricultural productivity, blind reclaiming made natural vegetation to be destroyed, then new cultivated land was quickly rejected and desertification was occurred owing to lacking of protective system and mis-management of water resources. The animal husbandry and agricultural area was unsuitably developed because of the unbalanced condition between grass production and livestock carrying capacity, with the result that desert vegetation was destroyed. Population growth caused great demand to living resources in plunder-like way. Secondly, in order to increase agricultural production, plantation was neglected. Ecological benefit and oasis protection was weakened due to the irrational distribution of water resources. And as a result of less strategic consideration on the protective system of oasis, the process of desertification resulting from natural condition (mainly climate factor) was also accelerated. The above-mentioned human and natural factors are the root causes of desertification in the project area.
Situated on the southern fringe of the Taklimakan Desert, the Cele County belongs to the extra-arid desert zone. Being very poor in water resources for planting trees and grass in spring and autumn, the coverage of vegetation in this region is only 0.24%. With fine particles of sand material, rich sand sources and frequent winds and sand movements, the unreasonable human activities accelerate the process of desertification. According to the natural condition of the projected area, starting with restoring natural vegetation and developing artificial vegetation through making full use of rich floodwaters, this project was aimed to solve the problem of shortage of protective system at the periphery of desert oasis. This project did not only extend coverage of vegetation and control the expansion of shifting sands and reduce the threat of the city being buried under sand accumulation, but also did protect and enlarge the extend of the oasis. It should be mentioned that the sand stabilization system has established protective system for controlling sand movements and has supported the artificial seeding over large areas using summer floodwater in the plantation, which represents the latest achievements for creating approaches to establish protective system and preventing oasis from sand accumulation.
5.1 Design and plan of the
integrated sand stabilization system
Through six-years’ efforts, an integrated sand stabilization system with an area of 10,000 ha has been established at the periphery of oasis, which forming a green belt in 4.5-km width mainly composed of grass and bushes (accounting for 77%). The system is consisted of the flood flows channels the sand-fixing grass and bushes belt, the artificial plantation of bush and the narrow-belt and multi-belt sandbreaks. Since each of its components reduced wind force successively and stopped sand movements, the system has effectively reduced the expansion of shifting sands and the sand invasion, which played a remarkable role in declining wind velocity and improving the micro-climate conditions of farming ecosystem in oasis.
5.2 Practice on afforestation
with summer floodwater
The project was successfully implemented through artificial plantation of desert shrubs with summer floodwater. Meanwhile, further researches on the technology of afforestation, such as the types of plantation, the treatment of seeds, etc. , were conducted and rich experiences have been achieved. The operation of the project has opened a new way for planting desert vegetation in regions with sufficient floodwater in summer. Especially the direct seeding with summer floodwater is easy to be extended at farmers’ level in consideration of lower cost and a fruit result.
5.3 Promotion of
restoration of natural vegetation and its rational utilization
In light to restore vegetation, grand total of 13.2 km of trunk canal, 29 km of lateral canal and branch canal, 153 sluice gates, and 44 bridges have been constructed by the end of 1987, which forming a sound irrigation system. Taking the way of irrigation with floodwater and artificial re-seeding, 10,000 ha of desert land was revegetated, the vegetative coverage was increased by 50-60% in 1987 from 3-5% in early years. Among the restored vegetation, the plant community with Albagi pseudalhagi was the dominant species covered an area of about 3,333 ha, increasing coverage by 90-95%; the communities with other herbs covered an area of 666 ha, having coverage of 60-80%, the secondary young trees of Populus euphratic covered an area of 2,670 ha, consisting of 40 million preserved trees and having a height of 6-10 m; the community with Tamarix spp. is the dominant species covered an area of 3,300 ha, having coverage of 60-80%. The biomass per unit area of the artificial vegetation increased by over 50 times.
5.4 Improvement and
utilization of the sandy land
When shifting sands being stabilized, the fodder and green manure, such as lucerre, etc., were grown in open ground of the shelter belt network. This resulted in an improvement of the aeolian soil and an enhancement of the land fertility. On this basis, the horticulture and farming were developed. By 1988, an area of 68 ha has been planted fruits trees, consisting of 49,000 preserved trees, and 200 ha of the land improved by planting grass has been turned into a cultivated land.
5.5 Plantation technology
and rational utilization of windbreaks and sand-fixing fuelwood plantation
In order to meet the need both for sand fixing and fuelwood supplying, the pioneer sand-fixing shrubs that have a quick growth, with high value of fuelwood and strong regeneration were selected to be planted in large density and strip mixture. As a result, the total area of afforestation reached 200 ha.
5.6 Introduction of exotic
species, tree seedling and experiment of adaptability
In past years, more than 60 species were introduced, 50 species were successful, and the nursery area of the field planting was 2.7 ha, the species of seed selection that fit to be plant in local region are Calligonum caput-medusa, Calligonum arbores, Calligonum klementziia, Tamarix chinensis Locor, Tamarix elongala Ledeb, Tamarix taklimakanesis M. T. Liu, and so on.
With six-years’ efforts, the tangible social, ecological and economic benefits have been achieved.
6.1 Social benefits
The first model of large-scale shifting sand stabilization has been established in southern Xinjiang. It plays a typical demonstrative role in the fixation of blown sand calamity, in stopping movement of mobile dunes, and enabling the sustainable development in the Cele County. Meanwhile, it protects 38 villages and stable development of agriculture and livestock production. The Eco-environment with sound circulation was created, grain yield was increased by 1 to 4 times, and per capita income was increased from 90 RMB Yuan to 315 RMB Yuan. The poverty problem has been alleviated.
6.2 Ecological benefits
Each part of the integrated sand stabilization system reduces 30-50% of wind velocity. The coverage of the restored vegetation reaches 60%, and the humus layer on surface is over 6 cm, which can effectively control the surface wind-erosion and blown sand. The relative humidity increased by 5.5-17.5%, and the evaporation reduced by 75-189 mm. The temperature of land surface, air and upper soil layer was reduced. These resulted in the improvement of environment. With the comparison of soil analysis, in the process of blown sand control, the soil fertility was raised when the vegetation coverage was increased, sand disasters were controlled. Furthermore, when legume or green manure were planted, the soil fertility will be increased quickly. In the project area, the nutrient content in the soil planting Lucerne for 5 years is 0.12-0.28 higher than that of aeolian soil.
6.3 Direct economic
benefits
By 1988, nearly 4.9 million individual trees were preserved and its estimated value were about 7.35 million RMB Yuan. Annual grass production was 17,000 tons with a value of 0.34 million RMB Yuan. The value of fuelwood was about 4.24 million RMB Yuan. The output of fruit harvest was 0.39 million RMB Yuan. The area of farmland reclaimed was 200 ha with a value of 3 million RMB Yuan. The estimated total output was as high as 15.32 million RMB Yuan.
The project plays an active role in protecting the oasis and farmland, and in improving the communication and settlements, in preventing water resources and environment from degradation. The Calligonum communities have become a local tourist and relax spot for local residents. The project has strengthened not only the public awareness for protecting environment and faith in struggle against shifting sands, but also has experienced the severe disaster of dust bowl in May of 1986. The measures adapted by this project are practical and effective.
The evaluation of project has shown that the project is characterized by low costs, short implementation duration, rich harvests, suitable method and high value to popularize. From the beginning to the end of the project, the local government has invested 0.4 million RMB Yuan for artificial plantation, 0.4 million RMB Yuan for irrigation installation, 0.22 million RMB Yuan for research and demonstration, 0.15 million RMB Yuan for infrastructure; investment for water consumption and labor force amounted to 0.42 million RMB Yuan, all these totally amounts to 1.64 million RMB Yuan. By economic analysis of the project, the direct economic output is 12.32 million RMB Yuan; the ratio of input and output is 1:7.5. The area of improved land is more than 100 sq. km, the annual investment was about 15,000 RMB Yuan per sq. km.
During implementation of the project, achievements and techniques were actively popularized through presentation, mobile training on wheel, on-the-spot demonstration, guidance at project site, information dissemination, seeds and seedlings supply, and successfully applied in the Pishan, Hetian, Cele, Yutian, and Minfeng counties with similar natural conditions.